When the skin is exposed to ultraviolet light, UV photons (290 to 315 nm) pass through the skin. UV photons are known to photodegrade 7-dehydrocholesterol in cells and convert the photodegraded 7-dehydrocholesterol into previtamin D3, as a precursor of vitamin D, thereby promoting the biosynthesis of vitamin D in the body (Fed Proc. 1987; 46: 1876-1882).
Vitamin D is involved in cardiovascular diseases, bone formation, autoimmune disease inhibition, and the like. (December 2010, Hyun Cho, Medicine Department of Soonchunhyang University, RELATIONSHIP BETWEEN VITAMIN D AND VARIOUS DISEASES). It was reported that vitamin D deficiency increases the occurrence frequencies of cancers such as breast cancer and colorectal cancer (February 2012, Jihyun Lee, Konkuk University, ANTI-CANCER EFFECT OF VITAMIN D3 ON HUMAN MELANOMA CELLS).
In accordance with research on Korean adult men and women, it was reported that serum concentrations of vitamin D in about 50% of adult men and women aged 19 to 69 years did not exceed an appropriate level, 20 ng/ml, (Korean Journal of Community Nutrition, 2014; 19: 122-132).
Ultraviolet rays play an important role in stimulating biosynthesis of vitamin D in the skin, but induce melanin pigmentation, causing darkening of the skin (Biotechnol. Biochem., 74(5), 918-922, 2010). In addition, ultraviolet rays are known to promote skin aging by increasing the expression of collagenase and inhibiting collagen synthesis (J. Oleo Sci. 58(8)429-436 (2009).
When the skin is exposed to ultraviolet rays, the amount of an enzyme called matrix metalloproteinase-1 (MMP-1) is increased. Since this enzyme rapidly decomposes collagen, the skin loses elasticity and wrinkles.
Ultraviolet sunscreens are generally used for cosmetic purposes so as to suppress or avoid the side effects of ultraviolet rays. However, such an ultraviolet sunscreen includes benzophenone-3 (BP-3), 3-benzylidene camphor (3-BC), 3-(4-methyl-benzylidene) camphor (4-MBC), 2-ethylhexyl 4-methoxy cinnamate (OMC), homosalate (HMS), 22-ethylhexyl 4-dimethylaminobenzoate (OD-PABA), 4-aminobenzoic acid (PABA), and the like which are reported to be carcinogenic or affect the reproductive endocrine and thyroid endocrine systems of the body (Int J Androl. 2012; 35: 424-436).
Meanwhile, reactive oxygen species (ROS) in the body are naturally produced by normal metabolism of oxygen, but are also generated by external factors such as X-rays, ozone, smoke, air pollution, electromagnetic waves, residual pesticides, and stress.
These ROS, which contain oxygen ions and peroxides and are highly reactive substances oxidizing other substances in the body due to unpaired electrons (non-covalent electron pairs), may destroy normal cells.
Interestingly, melanin generation due to ultraviolet rays is caused by excessive pigmentation of the skin, and skin aging is known to be mediated by ROS.
Melanin is produced through a series of oxidation reactions of the amino acid tyrosine. Tyrosinase is known to play an important role in melanin generation. It was reported that, when the activity of the enzyme is regulated, excessive sedimentation is inhibited (J. Oleo, Sci. 58 (8), 429-436, 2009).
Meanwhile, superoxide dismutase, as the most potent antioxidant enzyme, converts superoxide anion radicals (O2−) generated by ultraviolet rays into less harmful hydrogen peroxide (H2O2) which is again decomposed into water and oxygen (2H2O2→2H2O+O2) by GPX and a catalase to be used for metabolism in the human body, thereby eliminating damages due to ROS.
In addition, superoxide dismutase (SOD) was investigated to suppress the production of alpha-melanocyte stimulating hormone and the increase of melanin production due to UV-B exposure.
Recent studies have reported that the antioxidative effects of hydrogen are caused by activity increase of superoxide dismutase (SOD) contained in blood (J. Clin. Biochem. Nutr. 46, 140-149, 2010, 3). Accordingly, hydrogen is considered to sufficiently complement the aforementioned superoxide dismutase functions.
Recently, many cases of utilizing hydrogen, which is generated through a simple chemical reaction (Mg+2H2O→Mg(OH)2+H2), for skin care and the like are reported in Japan and other countries. Hydrogen has been reported to have antioxidant effect of selectively reducing cytotoxicity of ROS that damage cells.
In addition, through animal experiments and human clinical trials in which drinking water including hydrogen (hydrogen rich water) was used, it was known that hydrogen therapy, which increases hydrogen supply, induces decrease in cytotoxicity and decrease in cytotoxicity due to carbon monoxide.
Meanwhile, phytoncides, as natural products, are volatile substances released from land plants and are known to inhibit the enzymatic activity of tyrosinase, as an important enzyme for the production of melanin. In addition, phytoncides were reported to inhibit cellular damage due to UV-A and UV-B, active oxygen (H2O2) and tert-butyl-hydroperoxide (t-BHP), and promote the generation of collagen in skin cells.
In addition, it was reported that, when the skin is exposed to ultraviolet rays, an enzyme called tyrosinase produces melanin, which darkens the skin, but phytoncides regulate the production of melanin by inhibiting the activity of tyrosinase.
It was reported that, when cellular damage due to oxidative stress was examined after phytoncides were applied to the normal skin and then the skin was irradiated with UV-B and UV-A, phytoncides extracted from cypress reduced a generation amount of an enzyme MMP-1 decomposing collagen in the normal skin by 83% or more when the skin is irradiated with UVA (J. Oleo Sci. 58 (8) 429-436, 2009).
In addition, phytoncides have been reported to have physiological effects, such as rapid anti-aging effect, alleviation of allergies, various cirrhosis types, Parkinson's disease, and the like, and activation of natural killer (NK) cells as immune cells.
Meanwhile, when phytoncides are directly applied to the skin, anti-wrinkle and antioxidant effects are exhibited. In addition, when phytoncides are sprayed along with hydrogen on the skin, the phytoncides and hydrogen are quickly absorbed into the skin.
As products on which the aforementioned points were reflected, spray-type products wherein phytoncides extracted from cypress were diluted to a concentration of 3% or less were manufactured. These spray-type products are generally composed of 97% of water and 3% of phytoncides. In the case in which only phytoncides are used, a general plastic container is used. In addition, since hydrogen is stored in a general plastic container also in the cases of products using hydrogen, there are few methods of preventing hydrogen leakage through pores of a wall of the plastic container.
Accordingly, the present inventors attempted to develop a phytoncide moisturizing liquid composition, a hydrogen-generating spray device for skin care including the same, and a method of manufacturing the same so as to allow effective use of the phytoncide moisturizing liquid composition without waste of hydrogen, and effective skin care due to effects, such as vitamin D synthesis, inhibition of melanin synthesis, inhibition of collagen decomposition, collagen synthesis, and decomposition of active oxygen, using synergistic effects of hydrogen and the phytoncide moisturizing liquid composition.